Package of filter tow bale packed with packing material in a non-hermetic state and manufacturing method thereof

ABSTRACT

The present invention provides a package of a filter tow bale made of cellulose acetate packed with a packing material in a non-hermetic state, which can be stacked in multistage and in which tows in the same bale can be uniformly maintained. The package of the filter tow bale made of cellulose acetate is packed with the packing material in the non-hermetic state, in which the filter tow bale is tightened with the packing material in the package, the filter tow bale has a cubic shape or a rectangular parallelepiped shape with 800 to 1,400 mm in length, 800 to 1,150 mm in width, and 800 to 1,100 mm in height, and a packing initial pressure between a top surface of the filter tow bale and the packing material is 6.3 kPa or less.

FIELD OF THE INVENTION

The present invention relates to a package of a filter tow bale packedwith a packing material in a non-hermetic state and a manufacturingmethod thereof.

BACKGROUND OF THE INVENTION

A bulky filter tow is packed in a state of compressed filter tow bale.

As packed tow bales are stored in a warehouse in a multistage stackedmanner, a technology for facilitating the multistage stacking isprovided.

In JP-A 2005-528096, there is disclosed a technology in which a tow baleis packaged with a plastic film and the inside of the tow bale is madeto be in a negative pressure state, thereby allowing a top surface and abottom surface of the tow bale to be flat surfaces.

In JP-A 2009-508764, there is disclosed an invention in which a fibermaterial is packaged after being compressed by use of a convex baleplaten to manufacture a fiber bale.

As shown in FIG. 2 and FIG. 3, the convex bale platen 18 has a shape inwhich the entire convex surface 20 is curved.

When the fiber material is compressed by using the convex bale platen 18having the above shape, a central part of the fiber material is stronglycompressed, and the compression in a peripheral part is low. Therefore,after releasing the compression, the degree of swelling in the centralpart is small and the swelling in the peripheral part is large. As aresult, the entire surface becomes flat.

In JP-A 2008-539143, there is disclosed a method of compressing a fibermaterial by using a platen.

SUMMARY OF THE INVENTION

In the technology of JP-A 2005-528096, when the plastic film is brokenat the time of works such as carrying the tow bales and stacking them inmultistage, the inner negative pressure state cannot be maintained, andthe flat surfaces cannot be maintained, either. Thus, it becomesdifficult to perform multistage stacking.

In the bale obtained by the manufacturing method as in JP-A 2009-508764,the elastic recovery force differs in the central part and theperipheral part, therefore, filter tows having different physicalproperties are mixed in one bale.

Accordingly, for example, when tobacco filters are manufactured by usingsuch bale as a raw material, a tension at which the tow is wound offfrom the bale varies. Thus, variation in mass per one filter isincreased, which increases variation in quality of the filters.

The method of JP-A 2008-539143 has a similar problem with that of JP-A2009-508764 as the platen itself used in the method of JP-A 2008-539143has a similar shape to the convex bale platen in JP-A 2009-508764.

An object of the present invention is to provide a package of a filtertow bale packed with a packing material in a non-hermetic state whichcan be stacked in multistage and can reduce variation in quality of towsin the same bale, a filter plug for tobacco obtained from the filter towbale of the package and a manufacturing method of the package packed inthe non-hermetic state.

According to an embodiment of the present invention, there is provided apackage of a filter tow bale made of cellulose acetate packed with apacking material in a non-hermetic state, in which:

the filter tow bale is tightened with the packing material in thepackage;

the filter tow bale has a cubic shape or a rectangular parallelepipedshape with 800 to 1,400 mm in length, 800 to 1,150 mm in width, and 800to 1,100 mm in height; and

a packing initial pressure between a top surface of the filter tow baleand the packing material is 6.3 kPa or less.

According to another embodiment of the present invention, there isprovided a filter plug for tobacco formed of a filter tow bale obtainedafter removing the packing material from the package of the filter towbale packed with the packing material in the non-hermetic state, inwhich:

the filter plug for tobacco has a variation in filtering resistance(PDCV) lower than 3.5 when it has a circumference of 20 to 25 mm and adensity of 400 to 600 kg/cm³; and

the filter plug for tobacco has a variation in filtering resistance(PDCV) lower than 3.5 when it has a circumference of 18 mm or less and adensity of 350 to 450 kg/cm³.

According to further another embodiment of the present invention, thereis provided a manufacturing method of the non-hermetic package of thefilter tow bale including:

a first step of depositing a band of filter tow into a compression canin layers;

a second step of compressing the layers of the deposited filter tow bandby pressing means composed only of a flat surface from an upper side sothat an impulse (N·s) calculated from the following formula is 1,500 ormore,

a third step of packing the filter tow bale in an unsealed state with apacking material after stopping the compression by the pressing meansand removing a cylindrical wall used for compression; and

a fourth step of lifting the pressing means and releasing the filter towbale from the pressure.

Impulse (N·s)=(height of convex portion(mm)/5.4+1)×force by pressingmeans at the time of compression(N=kg·m/s²)×compression time(s)

According to further another embodiment of the present invention, thereis provided a manufacturing method of the non-hermetic package of thefilter tow bale, including:

a first step of depositing a band of filter tow into a compression canin layers;

a second step of compressing the layers of the deposited filter tow bandby pressing means having a convex portion at a central part and a flatsurface portion at a peripheral part from an upper side;

a third step of packing the filter tow bale in an unsealed state with apacking material after stopping the compression by the pressing meansand removing a cylindrical wall used for compression; and

a fourth step of lifting the pressing means and releasing the filter towbale from the pressure.

The package of the filter tow bale packed with the packing material inthe non-hermetic state according to the present invention can be stackedin multistage, in which a variation in quality of filter tows in thesame bale is small.

Accordingly, the filter plug for tobacco according to the presentinvention obtained from the filter tow bale of the package has a smallvariation in filtering resistance.

BRIEF DESCRIPTION OF DRAWINGS

The present invention is understood by the following detaileddescription and attached drawings further completely, however, thesedrawings are attached only for explanation and do not limit the presentinvention.

FIG. 1 is a perspective view of a non-hermetic package of a filter towbale according to the present invention. Note that the drawing is shownin a state where part of a packing material is removed so that theinside is seen.

FIG. 2 is an explanatory view of a measuring method of a packing initialpressure between a top surface of the filter tow bale and the packingmaterial.

FIG. 3 is a view for explaining a manufacturing method of thenon-hermetic package of the filter tow bale according to the presentinvention.

FIG. 4(a) is a cross-sectional view of an upper pressing plate in athickness direction used in the manufacturing method according to thepresent invention, and FIG. 4(b) is a plan view of the upper pressingplate. In the drawings, a reference numeral 10 denotes a package, areference numeral 11 denotes a packing material, a reference numeral 12denotes a covering material, a reference numeral 13 denotes a tighteningmaterial, a reference numeral 15 denotes a filter tow bale, a referencenumeral 20 denotes a compression can, a reference numeral 21 denotes alower pressing plate (lower platen), a reference numeral 22 denotes anupper pressing plate (upper platen), a reference numeral 23 denotes aconvex portion, and a reference numeral 24 denotes an inclined surface.

DETAILED DESCRIPTION OF THE INVENTION

<Non-Hermetic Package of Filter Tow Bale>

A filter tow bale which is packed with a packing material in anon-hermetic state (hereinafter abbreviated as a “Package in aNon-hermetic State”) according to the present invention is in a statewhere a filter tow bale made of cellulose acetate is tightened with apacking material, and has flat surfaces in such a degree that multistagestacking is possible.

The “non-hermetic state” in the present invention means that a filtertow bale is covered with a packing material in a state where the filtertow bale can be aerated, and the technology of utilizing the negativepressure as packaging means disclosed in the invention of JP-A2005-528096 is not included.

Next, the Package in a Non-hermetic State according to the presentinvention will be explained with reference to FIG. 1.

In the Package in a Non-hermetic State 10, a filter tow bale 15 made ofcellulose acetate is tightened with a packing material 11.

The filter tow bale 15 has a cubic shape or a rectangular parallelepipedshape with 800 to 1,400 mm in length, 800 to 1,150 mm in width and 800to 1,100 mm in height.

As the packing material 11, a material containing a combination of acovering material 12 and a tightening material 13 can be used.

When the packing material 11 containing a combination of the coveringmaterial 12 and the tightening material 13 is used, the filter tow bale15 is covered with the covering material 12 and is tightened with thetightening material 13 over the covering material 12 as shown in FIG. 1.

As the covering material 12, a material selected from a thin film,paper, a corrugated fiberboard, a synthetic resin sheet, a woven fabric,a non-woven fabric and combinations of these can be used.

When using a synthetic resin sheet, a woven fabric or a non-woven fabricas the covering material, a material to which stretchability is impartedby adjusting the thickness, material quality, weaving method and so on,may be used.

When using a material to which stretchability is imparted is used as thecovering material, the covering material itself can also performtightening by covering the tow bale in a state where the coveringmaterial is stretched.

As the tightening material 13, a synthetic resin band or a metal bandcan be used.

A packing material comprising a combination of the covering material andmeans for integrating the covering material may be used instead of thecovering material 12 and the band 13 as the tightening material as shownin FIG. 1.

As the covering material, the same materials as described above can beused.

As the means for integration, means selected from a surface fastener, anadhesive and a heat seal can be used. The surface fastener performsintegration of end portions of the covering material which are close toeach other, and the adhesive and the heat seal perform integration ofoverlapped end portions of the covering material.

As the package 10 according to the present invention is in anon-hermetic state, it is not necessary that the filter tow bale 15 iscompletely covered with the covering material 12.

When the tow bale is completely covered with the covering material 12, amaterial having air permeability, or a material not having airpermeability and having a vent hole is used as the covering material 12.

A packing initial pressure between a top surface 15 a of the filter towbale 15 and the packing material 12 is 6.3 kPa or less in the package10.

Here, a “packing initial pressure” means a pressure after 10 minutesfrom the completion of packing (when a press pressure is released inFIG. 3(e)).

The “packing initial pressure” is measured by a method described inexamples, and is an average value of pressures at the total of threepoints, which are a circle (circle mark) 51 including the center pointof the top surface 15 a, and two points of circles (circle marks) 52 to55, as shown in FIG. 2.

While it is preferred that a central part and a peripheral part of a topsurface 10 a of the package 10 is flush with each other, the top surface10 a of the package 10 may have a central part being swollen as comparedwith a peripheral part as long as the degree of swelling is small.

In the case where the central part of the top surface 10 a is swollen ascompared with the peripheral part, the height of swelling at the centralpart is 25 mm or less when the peripheral part is taken as a reference.Even when the central part is swollen as described above, a work ofmultistage stacking can be facilitated as long as the degree of swellingcan be made small.

Unlike the bales as described in the inventions of JP-A 2009-508764 andJP-A 2008-539143 in which the degree of swelling at the central part issmall and the degree of swelling in the peripheral part is large tothereby form the flat surface, the package 10 according to the presentinvention has the central part being flush with the peripheral part orthe central part being slightly swollen as compared with the peripheralpart. Therefore, a variation in the elastic recovery force in the sametow bale 15 is small.

Accordingly, a fluctuation in tension is small when unwinding the towfrom the tow bale 15, therefore, a fluctuation in mass per one filter isalso small, thereby obtaining uniform filters.

The filter plug obtained by using the tow bale 15 of the package 10according to the present invention has a variation in filteringresistance (PDCV) lower than 3.5 when it has a circumference of 20 to 25mm and a density of 400 to 600 kg/cm³, and the filter plug has avariation in filtering resistance (PDCV) lower than 3.5 when it has acircumference of 18 mm or less and a density of 350 to 450 kg/cm³.

<Manufacturing Method of Package>

A manufacturing method of the package of the filter tow bale in thenon-hermetic state will be explained with reference to FIGS. 3(a) to(f).

[First Step]

In the first step, a band of filter tow is deposited into a compressioncan 20 in layers (layers of filter tow 30) as shown in FIG. 3(a).

As a tow for filters, for example, a tow having the total denier of15,000 to 45,000, in which 2,000 to 30,000 pieces of filaments having afilament denier of 1.5 to 8.2 are gathered, can be used.

When used as a production raw material of a tobacco filter plug, a towfor filters having different filament deniers can be used according tothe width of the tobacco filter plug.

When used for the filter plug having a circumference of 20 to 25 mm anda density of 400 to 600 kg/cm³, a tow for filters having a filamentdenier of 2.0 to 3.5 and the total denier of 30,000 to 40,000 ispreferred.

Further, when used for the filter plug having a circumference of 18 mmor less and a density of 350 to 450 kg/cm³, a tow for filters having afilament denier of 3.6 to 8.2 and the total denier of 30,000 to 40,000is preferred.

After that, the compression can 20 filled with the layers of filter tow30 is moved to a place where a lower pressing plate (lower platen) 21and an upper pressing plate (upper platen) 22 are arranged opposite toeach other in a height direction and placed on the lower pressing plate21 as shown in FIG. 3(b).

The lower pressing plate 21 is a flat plate.

A packing material (covering material) (not shown) and a synthetic resinband 40 serving as a tightening material are arranged on the lowerpressing plate 21. The synthetic resin band 40 is inserted into aplurality of grooves 26 formed in the lower pressing plate 21.

The method itself in which a material corresponding to the packingmaterial is previously arranged in pressing means is well known anddescribed in, for example, JP-A 2010-254376 and shown in FIG. 2, anddescribed in JP-A 2011-213354 and shown in FIG. 2 and FIG. 4.

[Second Step]

In the second step, the layers of filter tow 30 are compressed by theupper pressing plate 22 from an upper side as shown in FIG. 3(c).

The upper pressing plate 22 can apply a pressure by a hydraulic rod 25.

The upper pressing plate 22 has a convex portion 23 in the central partand has a flat surface portion 24 in a peripheral part.

The convex portion 23 and the flat surface portion 24 have the pluralityof grooves 26 for inserting the synthetic resin band 40, and thesynthetic resin band 40 serving as the tightening material is insertedinto the grooves 26.

In one example, the convex portion 23 is a mountain-like protrusionhaving an inclined surface or a stepped surface. That is, the convexportion 23 includes a flat top surface 23 a and an inclined surface 23 bas shown in FIGS. 4(a), (b). The inclined surface 23 b may also be astepped surface.

A height H of the convex portion 23 from the flat surface portion 24 ispreferably 0 to 40 mm, and more preferably 5 to 40 mm and furtherpreferably 10 to 38 mm.

As an area ratio between the convex portion 23 and the flat surfaceportion 24 in the upper pressing plate 22, an area of the convex portion23 is preferably 95% or more, and more preferably, 98% or more.

As an area ratio between the top surface 23 a and the inclined surface23 b in the convex portion 23, an area of the flat top surface 23 a ispreferably 10 to 40%, and more preferably, 15 to 30%.

In the second step, compression is performed so that an impulse (N·s)calculated from the following formula is preferably 1,500 N·s or more,and more preferably, 1,500 to 15,000 N·s.

Impulse (N·s)=(height of convex portion(mm)/5.4+1)×force by pressingmeans at the time of compression (N=kg·m/s²)×compression time(s)

(5.4 and 1 in the formula are constants based on manufacture dataaccumulated for a long period of time, which indicate a known impulse(hereinafter “impulse 1”) obtained from the force by the pressing meansat the time of compression (N=kg·m/s²)×compression time (s).)

In the second step, a plate composed only of a flat surface (not havingthe convex portion 23) can be used as the upper pressing plate 22.

When using the upper pressing plate 22 composed only of the flatsurface, compression is performed so that a prescribed impulse isobtained.

[Third Step]

In the third step, as shown in FIG. 3(d), after the compression by theupper pressing plate 22 is stopped, the compression can 20 used forcompression is moved and removed, then, the filter tow bale 15 is packedwith the packing material (only the synthetic resin band 40 is shown inthe drawing) so that the filter tow bale 15 is in a non-hermetic state.

To stop the compression in the third step means to stop applying thepressure by the hydraulic rod 25. As the upper pressing plate 22 itselfis in the state of FIG. 3(d), the filter tow bale 15 is in a state whereat least a pressure by an own weight of the upper pressing plate 22 isapplied.

In the state shown in FIG. 3(d), packing is performed so that a packinginitial pressure between the top surface 15 a of the filter tow bale 15and the packing material 12 is 6.3 kPa or less.

[Fourth Step]

In the fourth step, the filter tow bale is released from the pressure bylifting the upper pressing plate 22 to thereby obtain the package 10 asshown in FIGS. 3(e), (f).

While the top surface 10 a of the package 10 is a flat surface in thestate shown in FIG. 3(e) obtained immediately after the upper pressingplate 22 is lifted, the central part of the top surface 10 a may beslightly swollen with a lapse of time.

However, since a height of swelling at the central part at this time is25 mm or less when the peripheral part is taken as a reference, the workof multistage stacking is facilitated.

EXAMPLES Examples 1 to 7 and Comparative Examples 1 to 8

Packages of examples and comparative examples were fabricated by thesteps shown in FIGS. 3(a) to (f).

[First Step: FIGS. 3(a), (b)]

A filter tow having a filament denier of 2.0 to 3.5 and the total denierof 30,000 to 40,000 was used.

The compression can 20 made of metal having a rectangular parallelepipedshape with 1,200 mm in a long edge, 950 mm in a short edge and 4,000 mmin height was used, and a filter tow of 625 kg was put into the can.

[Second Step: FIG. 3(c)]

As shown in FIG. 3(c), the layers of tow 30 were compressed by the upperpressing plate 22 in compression conditions shown in Table 1 to obtainbales with a packing density of 550 kg/m³.

The upper pressing plate 22 composed only of the flat surface (theheight (H) of the convex portion is 0 mm in Table 1) was used in theexamples 1, 2 and the comparative examples 1 to 3.

In other examples, the upper pressing plate 22 having the convex portion23 as shown in FIG. 3 was used. The heights (H) of the convex portionsare shown in Table 1.

[Third Step; FIG. 3(d)]

After a compression time shown in Table 1 was passed, packing wasperformed by strapping bands from directions orthogonal to each other asshown in FIG. 1 so as to be in the non-hermetic state.

Two pieces of a film made of polyethylene resin and an inserting paper(the inserting paper is arranged in the outside) were used as thecovering material 12, and five bands made of polyethylene-telephthalateresin (width 15 mm) were used as the synthetic resin band 13 (two bandsin the same direction and three bands in orthogonal direction wereused).

[Fourth Step; FIGS. 3(e), (f)]

After the packing, the pressure was released to obtain the package 10.

The packing initial pressure of the package 10 was measured.

In addition, after allowing the obtained package to stand for 24 hoursat room temperature, a swelling on the top surface was measured. Theswelling on the top surface was provided by placing a flat plate (10 kg)on the top surface and measuring distances between four corners and theflat plate to obtain an average value thereof.

<Measuring Method of Packing Initial Pressure>

Measurement was made by using a film-type sensor having 14 mm in width,205 mm in length and 0.208 mm in thickness (a circle having a diameterof 9.5 mm at the tip of the sensor is an effective sensing area, themaximum loads 4.4 N and 110 N; pressure-voltage conversion type) (brandname: Flexi Force, manufactured by NITTA Corporation).

The measurement was made 10 minutes after the release of pressure in thestep of FIG. 3(e).

As the measurement method, the covering material was cut forapproximately 20 mm in the vicinity of three points of the circle 51,the circle 53 and the circle 55 shown in FIG. 2, and measurement wasperformed by inserting the film-type sensor so that the effectivesensing area (connected to an external circuit) was positioned at thecircle 51, the circle 53 and the circle 55.

The synthetic resin band 13 does not exist at positions of the circle51, the circle 53 and the circle 55.

Test Example 1 (Evaluation of Multistage Stacking Property)

Stability when stacking packages in four stages was evaluated by usingthe obtained packages. Wooden pallets were interposed between a floorsurface and the lowermost package and between respective packages.

In the four-stage stacking as the above, states of contacts between thepallets interposed between respective packages and the top surfaces ofthe packages were observed by the naked eyes and evaluated. Packages inwhich the pallet contacts the top surface of the package were evaluatedas “good,” while packages in which the pallet does not contact the topsurface even in a part were evaluated as “poor.”

Text Example 2 (Evaluation of Pressure Drop When Processed Into TobaccoFilter)

Pressure drop was evaluated when the tow bales of respective packagesaccording to the examples and the comparative examples were used andprocessed into tobacco filters.

A tow of cellulose acetate fiber was opened or bloomed using a rodmaking machine for manufacturing tobacco filters (KDF2/AF1) to haveapproximately 5 cm to 20 cm in width, and after uniformly spraying 6parts by mass of triacetin relative to 100 parts by mass of the tow, thetow was opened or bloomed with an air stream, introduced into atrumpet-shaped convergence tube, wound up using wrapping paper, and thencut by a cutter, thereby to obtain a filter.

A filter rod having a circumference of 24.2 mm and a length of 100 mmwas obtained. The winding velocity was 600 m/min.

A pressure drop (mmWG) relating to the filter rod having the length of100 mm was measured by using an automatic pressure drop measuringinstrument (“QTM-6” manufactured by CERULEAN UK) in a condition of anair flow rate 17.5 ml/sec).

Average values (x) and standard deviations (a) of the pressure drop (PD)were calculated from measurement data, and PDCV was calculated by aformula: σ/x ×100.

Evaluations were indicated as “good” when PDCV was lower than 3.5 andevaluations were indicated as “poor” when PDCV exceeded 3.5. When PDCVis lower than 3.5, the smoking flavor obtained when using as the tobaccofilter is not badly affected.

TABLE 1 Second step Package Test result Convex Pressing CompressionCompression Impulse Packing initial Multistage portion (H) area pressuretime (H/5.4 + 1) × pressure Swelling stacking height (mm) (m²) (MPa)(second) Impulse 1 Impulse 1 (MPa) height (mm) property PDCV Example 1 01.13 3.5 600 1526 1,526 5 25 Good Good Example 2 0 1.13 3.5 2100 16754,675 5 20 Good Good Comparative 0 1.13 3.5 60 187 187 40 45 Poor GoodExample 1 Comparative 0 1.13 3.5 240 666 666 25 30 Poor Good Example 2Comparative 0 1.06 1.3 120 133 133 50 60 Poor Good Example 3 Example 310 1.13 3.5 360 962 2,744 5 25 Good Good Comparative 10 1.06 1.3 180 192548 30 38 Poor — Example 4 Comparative 10 1.13 3.5 60 187 534 30 35 Poor— Example 5 Example 4 25 1.13 35 240 666 3,750 5 25 Good — Comparative25 1.13 35 60 187 1,054 15 35 Poor — Example 6 Example 5 38 1.13 3.5 60187 1,504 5 25 Good Good Example 6 38 1.13 3.5 240 666 5,353 5 20 GoodGood Example 7 38 1.13 3.5 600 1526 12,268 5 20 Good Good Comparative 381.06 1.3 120 133 1,066 15 30 Poor Good Example 7 Comparative 60 1.13 3.560 187 2,267 5 25 Good Poor Example 8

As apparent from Table 1, in packages according to the presentinvention, heights of swelling in the central part were low (25 mm orless), therefore, both the multistage stacking property and PDCV whenprocessed into the tobacco filters were good.

From comparison between examples 1, 2 and examples 3 to 7, it was foundthat using the pressing means having the convex portion in the centralpart and the flat surface portion in the peripheral part was apreferable manufacturing method in consideration of the number ofequipment needed at the time of manufacture as the compression time wasreduced.

Examples 8 to 10 and Comparative Examples 9 to 13

Packages of examples and comparative examples were fabricated by stepsshown in FIGS. 3(a) to (f).

[First Step; FIGS. 3(a), (b)]

Filter tows having filament deniers and total deniers shown in Table 2were used.

The compression can 20 made of metal having a rectangular parallelepipedshape with 1,200 mm in a long edge, 950 mm in a short edge and 4,000 mmin a height was used, and a filter tow of 625 kg was put into the can.

[Second Step; FIG. 3(c)]

As shown in FIG. 3(c), the layers of tow 30 were compressed by the upperpressing plate 22 in compression conditions shown in Table 1 to obtainbales with packing densities shown in Table 2.

The upper pressing plate 22 composed only of the flat surface (theheight (H) of the convex portion is 0 mm in Table 1) was used in theexample 9 and the comparative examples 9 to 11, 13.

In other examples, the upper pressing plate 22 having the convex portion23 as shown in FIG. 3 was used. The heights (H) of the convex portionsare shown in Table 1.

[Third Step; FIG. 3(d)]

After a compression time shown in Table 3 was passed, packing wasperformed by strapping bands from directions orthogonal to each other asshown in FIG. 1 so as to be in the non-hermetic state.

Two pieces of a film made of polyethylene resin and an inserting paper(the inserting paper is arranged in the outside) were used as thecovering material 12, and five bands made of polyethylene-telephthalateresin (width 15 mm) were used as the synthetic resin band 13 (two bandsin the same direction and three bands in orthogonal direction wereused).

[Fourth Step; FIGS. 3(e), (f)]

After the packing, the pressure was released to obtain the package 10.

The packing initial pressure of the package 10 was measured.

In addition, after allowing the obtained package to stand for 24 hoursat room temperature, a swelling on the top surface was measured. Theswelling on the top surface was provided by placing a flat plate (10 kg)on the top surface and measuring distances between four corners and theflat plate to obtain an average value thereof.

Evaluation of the multistage stacking property of the test example 1 wasmade by using respective packages of the examples and the comparativeexamples. Results are shown in Table 3.

By a test example 2, pressure drop was evaluated when the tow bales ofrespective packages according to the examples and the comparativeexamples were used and processed into tobacco filters. A filter rodhaving a circumference of 16.5 mm and a length of 100 mm was fabricatedand used in the test example 2. Results were shown in Table 3.

TABLE 2 Filament Packing density denier Total denier (kg/m³) Example 8 617,300 450 Example 9 6 17,300 400 Example 10 6 17,300 350 Comparative3.1 29,800 500 Example 9 Comparative 6 17,300 400 Example 10 Comparative6 17,300 390 Example 11 Comparative 6 17,300 400 Example 12 Comparative6 17,300 500 Example 13

TABLE 3 Second step Package Test result Convex Pressing CompressionImpulse Packing initial Multistage portion (H) area Compression time(H/5.4 + 1) × pressure Swelling stacking height (mm) (m²) pressure (MPa)(second) Impulse 1 Impulse 1 (kPa) height (mm) property PDCV Example 838 1.13 3.5 60 187 1,504 5 25 Good Good Example 9 0 1.13 3.5 600 1,5261,526 5 25 Good Good Example 10 38 1.13 3.5 600 1,526 12,268 5 20 GoodGood Comparative 0 1.13 3.5 600 1,526 1,526 5 25 Good burst Example 9Comparative 0 1.13 3.5 60 187 187 40 45 Poor Good Example 10 Comparative0 1.06 1.3 120 133 133 50 60 Poor Good Example 11 Comparative 60 1.133.5 60 187 2,267 5 25 Good Poor Example 12 Comparative 0 1.13 3.5 60 187187 60 60 Poor Poor Example 13

As apparent from Table 3, heights of the swelling in the central partwere low (25 mm or less) in the packages according to the presentinvention, therefore, both the multistage stacking property and PDCVwhen processed into the tobacco filter were good.

From comparison between example 8 and example 9, it was found that usingthe pressing means having the convex portion in the central part and theflat surface portion in the peripheral part was a preferablemanufacturing method in consideration of the number of equipment neededat the time of manufacture as the compression time was reduced.

Furthermore, it was confirmed that, with the filter tows havingdifferent thicknesses (different filament deniers) used in the examples1 to 7 in Table 1 and the examples 8 to 10 in Table 3, the same resultswere obtained by adopting the manufacturing method according to thepresent invention.

Variation in quality of filter tows in the same bale is small in thepackages in which the filter tow bale is packed with the packingmaterial in the non-hermetic state, therefore, the filter tow bale ofthe package can be used as the filter plug for tobacco.

The present invention has been described as the above. The presentinvention naturally includes various modifications in a range thereof,and these modifications do not depart from the range thereof. Allregarded as modifications of the present invention by those who havenormal knowledge in the technical field is included in the range ofclaims described below.

1. A package of a filter tow bale made of cellulose acetate packed witha packing material in a non-hermetic state, wherein the filter tow baleis tightened with the packing material in the package, the filter towbale has a cubic shape or a rectangular parallelepiped shape with 800 to1,400 mm in length, 800 to 1,150 mm in width, and 800 to 1,100 mm inheight, and a packing initial pressure between a top surface of thefilter tow bale and the packing material is 6.3 kPa or less.
 2. Thepackage of the filter tow bale packed with the packing material in thenon-hermetic state according to claim 1, wherein the non-hermeticpackage of the filter tow bale has a central part of the top surfaceswollen as compared with a peripheral part, and a height of swelling atthe central part is 25 mm or less when the peripheral part is taken as areference.
 3. The package of the filter tow bale packed with the packingmaterial in the non-hermetic state according to claim 1, wherein thepacking material comprises a combination of a covering material and atightening material, and the filter tow bale is covered with thecovering material and the tightening material is tightened over thecovering material in the package.
 4. The package of the filter tow balepacked with the packing material in the non-hermetic state according toclaim 3, wherein the covering material is selected from a thin film,paper, a corrugated fiberboard, a synthetic resin sheet, a woven fabric,a non-woven fabric and combinations of these, and the tighteningmaterial is a synthetic resin band or a metal band.
 5. The package ofthe filter tow bale packed with the packing material in the non-hermeticstate according to claim 1, wherein the packing material comprises acombination of the covering material and means for integrating thecovering material, the covering material is selected from a thin film,paper, a corrugated fiberboard, a synthetic resin sheet, a woven fabric,a non-woven fabric and combinations of these, and the means forintegrating the covering material is selected from a surface fastener,an adhesive and a heat seal.
 6. The package of the filter tow balepacked with the packing material in the non-hermetic state according toany claim 3, wherein the covering material is formed of a materialhaving air permeability, or a material not having air permeability andhaving a vent hole.
 7. A filter plug for tobacco formed of a filter towbale obtained after removing the packing material from the package ofthe filter tow bale packed with the packing material in the non-hermeticstate according to claim 1, wherein the filter plug for tobacco has avariation in filtering resistance (PDCV) lower than 3.5 when it has acircumference of 20 to 25 mm and a density of 400 to 600 kg/cm³, and thefilter plug for tobacco has a variation in filtering resistance (PDCV)lower than 3.5 when it has a circumference of 18 mm or less and adensity of 350 to 450 kg/cm³.
 8. A manufacturing method of thenon-hermetic package of the filter tow bale according to claim 1,comprising: a first step of depositing a band of filter tow into acompression can in layers; a second step of compressing the layers ofthe deposited filter tow band by pressing means composed only of a flatsurface from an upper side so that an impulse (N·s) calculated from thefollowing formula is 1,500 or more; a third step of packing the filtertow bale in an non-hermetic state with a packing material after stoppingthe compression by the pressing means and removing the compression canused for compression; and a fourth step of lifting the pressing meansand releasing the filter tow bale from the pressure.Impulse (N·s)=(height of convex portion(mm)/5.4+1)×force by pressingmeans at the time of compression(N=kg·m/s²)×compression time(s).
 9. Amanufacturing method of the non-hermetic package of the filter tow baleaccording to claim 1, comprising: a first step of depositing a band offilter tow into a compression can in layers; a second step ofcompressing the layers of the deposited filter tow band by pressingmeans having a convex portion at a central part and a flat surfaceportion at a peripheral part from an upper side; a third step of packingthe filter tow bale in an non-hermetic state with a packing materialafter stopping the compression by the pressing means and removing thecompression can used for compression; and a fourth step of lifting thepressing means and releasing the filter tow bale from the pressure. 10.The manufacturing method of the non-hermetic package of the filter towbale according to claim 9, wherein, in the pressing means used in thesecond step, a height of the convex portion from the flat surfaceportion is 5 to 40 mm.
 11. The manufacturing method of the non-hermeticpackage of the filter tow bale according to claim 9, wherein, in thepressing means used in the second step, the convex portion is amountain-like protrusion including an inclined surface or a steppedsurface.
 12. The manufacturing method of the non-hermetic package of thefilter tow bale according to claim 9, wherein the compression isperformed by the pressing means so that an impulse (N·s) calculated fromthe following formula is 1,500 or more in the second step.Impulse (N·s)=(height of convex portion(mm)/5.4+1)×force by pressingmeans at the time of compression(N=kg·m/s²)×compression time(s).
 13. Thepackage of the filter tow bale packed with the packing material in thenon-hermetic state according to claim 2, wherein the packing materialcomprises a combination of a covering material and a tighteningmaterial, and the filter tow bale is covered with the covering materialand the tightening material is tightened over the covering material inthe package.
 14. The package of the filter tow bale packed with thepacking material in the non-hermetic state according to claim 2, whereinthe packing material comprises a combination of the covering materialand means for integrating the covering material, the covering materialis selected from a thin film, paper, a corrugated fiberboard, asynthetic resin sheet, a woven fabric, a non-woven fabric andcombinations of these, and the means for integrating the coveringmaterial is selected from a surface fastener, an adhesive and a heatseal.
 15. The package of the filter tow bale packed with the packingmaterial in the non-hermetic state according to any claim 4, wherein thecovering material is formed of a material having air permeability, or amaterial not having air permeability and having a vent hole.
 16. Thepackage of the filter tow bale packed with the packing material in thenon-hermetic state according to any claim 5, wherein the coveringmaterial is formed of a material having air permeability, or a materialnot having air permeability and having a vent hole.
 17. A filter plugfor tobacco formed of a filter tow bale obtained after removing thepacking material from the package of the filter tow bale packed with thepacking material in the non-hermetic state according to claim 2, whereinthe filter plug for tobacco has a variation in filtering resistance(PDCV) lower than 3.5 when it has a circumference of 20 to 25 mm and adensity of 400 to 600 kg/cm³, and the filter plug for tobacco has avariation in filtering resistance (PDCV) lower than 3.5 when it has acircumference of 18 mm or less and a density of 350 to 450 kg/cm³.
 18. Afilter plug for tobacco formed of a filter tow bale obtained afterremoving the packing material from the package of the filter tow balepacked with the packing material in the non-hermetic state according toclaim 3, wherein the filter plug for tobacco has a variation infiltering resistance (PDCV) lower than 3.5 when it has a circumferenceof 20 to 25 mm and a density of 400 to 600 kg/cm³, and the filter plugfor tobacco has a variation in filtering resistance (PDCV) lower than3.5 when it has a circumference of 18 mm or less and a density of 350 to450 kg/cm³.
 19. A filter plug for tobacco formed of a filter tow baleobtained after removing the packing material from the package of thefilter tow bale packed with the packing material in the non-hermeticstate according to claim 4, wherein the filter plug for tobacco has avariation in filtering resistance (PDCV) lower than 3.5 when it has acircumference of 20 to 25 mm and a density of 400 to 600 kg/cm³, and thefilter plug for tobacco has a variation in filtering resistance (PDCV)lower than 3.5 when it has a circumference of 18 mm or less and adensity of 350 to 450 kg/cm³.
 20. A filter plug for tobacco formed of afilter tow bale obtained after removing the packing material from thepackage of the filter tow bale packed with the packing material in thenon-hermetic state according to claim 5, wherein the filter plug fortobacco has a variation in filtering resistance (PDCV) lower than 3.5when it has a circumference of 20 to 25 mm and a density of 400 to 600kg/cm³, and the filter plug for tobacco has a variation in filteringresistance (PDCV) lower than 3.5 when it has a circumference of 18 mm orless and a density of 350 to 450 kg/cm³.